Mercury feeding apparatus



April 24, 1945. Q E, QWINGS MERCURY FEEDING APPARATUS Filed Dec. 1, 1943L/NE lnvervtor .m W W n w n 1 wfim m n H c b LINE 8 electrodes.

?atcnied Apr. 24, 1%5

STATES NT @FEEQE Charles E. Owings, Cleveland, Ohio, assignor to GeneralElectric Company, a corporation of New York Application December 1,1943, Serial No. 512,-4'l1 13 Claims.

My invention relates in general to the manufacture of electric dischargelamps or devices of the type comprising a sealed envelope containing apredetermined quantity of a vaporizable metal such as mercury. Morparticularly, my invention relates to method and apparatus forintroducing a predetermined quantity of vaporizable metal into theenvelope of such devices.

In the manufacture of electric discharge lamps ofthe well-knownfluorescent type in general use at present, a quantity of mercury isintroduced into the lamp envelope during the lamp exhaustlng operation.To insure a properly performing lamp, the quantity of mercury whichactually passes into and remains within the lamp envelope must be at orabove a certain minimum amount.

In the usual type of exhausting and mercury filling machine employed inthe manufacture of such fluorescent lamps, the electrodes of the lampare heated followirm the mercury filling operation by an electricalcurrent passing through the The mercury is introduced into the envelopeby means of an injecting device or dispenser which deposits a measuredamount of mercury into a vertical conduit communicating with theinterior of the envelope, the mercury dropping through the conduit intothe envelope and lodging within the lower end of the latter where it isvaporized by reason of the heated condition of the envelope andelectrode at the lower end of the lamp. If the mercury released by thedispenser into the conduit actually passes into the lamp envelope, anarc will eventually strike across the ends of each of the energized lampelectrodes due to the lower resistance of the mercury vapor arc paththereacross. Such a local arc discharge thus causes an end glOW todevelop within the lamp envelope. For various reasons, however, such asfailure of the mercury dispenser to operate properly or lodging of themercury elsewhere, a sufficient amount of the mercury released by thedispenser doe not always pass into the lamp envelope with the resultthat it is frequently necessary for the operator to perform additionalmanually-controlled mercury injecting operations, as,by hand switches.The determination of'whether or not additional mercury is to beintroduced into a lamp by the operation of such manually-controlledinjecting means there'- fore requires the constant observance by theoperator of either the lamps being processed or of suitable indicatormeans.

One object of my invention is to provide a] method and apparatus forautomatically introducing into the envelope of an electric dischargedevice a predetermined minimum quantity of a vaporizable metal.

Another object of my invention is to provide a mercury vapor lampexhaust apparatus having means for automatically effecting theintroduction of additional amounts of mercury into the lamp envelope inthe event a predetermined minimum amount of mercury is not initiallyintroduced thereinto.

, Still another object of my invention is to provide an indexing typelamp exhaust machine having, in combination, means for automaticallyfeeding a predetermined quantity of mercury to the envelope of a lampwhen positioned at one of thestations of said machine together withadditional means for automatically fiecting the introduction at asubsequent station of additional amounts of mercury into the lampenvelope in the event that a predetermineed minimum amount of mercury isnot then present in the lamp.

A featureof the invention is the provision of means controlled byelectrical condition existing within the lamp envelope for effecting.the automatic introduction of the additional mercury into the lampenvelope.

Further objects and advantages of my invention will appear from thefollowing description of a species thereof and from the accompanyingdrawing in which:

Fig. 1 is a diagrammatic representation of an exhaust machine head withassociated control 7 to a lamp exhaust machine of the type described andclaimed in United States Patent No. 2,247,513-A. J. Marshaus, issuedJuly 1, 1941,

, and comprising a, carrier or turret l0 having a plurality of heads I Iwhich are mountedat regularly spaced intervals about the periphery ofthe turret and are advanced in turn through a. similar number ofstations by counterclockwise indexing movements of the turret. As shownin Fig. 1, each head It is provided with suitable holders I! forcarrying an electric discharge lamp is which may be of the well-knownfluoionizing potential of mercury. The envelope l4 is completely sealedexcept for. the opening through an exhaust tube I'I extending from oneend of the envelope. The lamp I3 is held by the holders l2 in a verticalposition in the head II with the exhaust tube I'I uppermost andextending into a compression rubber chuck l8 mounted on the lower end ofan exhaust head IS. The chuck I8 is provided with a compressible rubberring 2ll which is mounted within the chuck housing 2| and is compressedtightly around the exhaust tube I! to thereby provide an airtightconnection between the exhaust tube and the chuck housing 2|. The rubberring is compressed by rotation of a cap 22 threaded onto the chuckhousing 2|, the said cap pressing a metal guide washer 23 up against theunderside of the rubber ring through ballbearings 24 interposed betweenthe cap and washer.

The chuck housing 2| is provided with an exhaust passageway 25 in axialalignment with both the exhaust tube I1 and a vertically extendingpassageway 26 in the exhaust head l9. Thesaid exhaust passageway 28 isformed, in part, by the opening through a rubber tube 21 disposedlongitudin l y within the exhaust head. and is connected to suitableexhausting means, such as a vacuum pump. through a connection pipe orconduit 23 and a rotary valve mechanism (not shown), as described "inthe previouslymentioned Marshaus patent. In case there be no lamp in thehead II, the operator can. close.

or pinch of! the passageway 23 in the exhaust head I 3 by means of. apinch clamp comprising a pressure member 29 and an actuating cam orlever 30 for pressing the pressure member 23 against the rubber tube 21to flatten the same and thus close or pinch of! the passageway a,predetermined-amount d mercury, extends through and has a free butsufflciently close sliding fit in the restricted upper end portion 38 ofthedischarge passageway to form an effective mercurytight sealtherebetween. The said slide member 36 is vertically reciprocable in thereservoir 33 to first introduce the recessed portion 31 thereof into themercury pool 34 so as to allow the recess 31 to fill with mercury and tothen withdraw the recessed portion down through and beyond the lower endof the restricted portion 38 of the discharge passageway 35 to therebyallow the mercury trapped in the recess to drop out .of said recess andinto the exhaust passageway 26. The slide member 35 extends up throughthe reservoir 33 and is connected at its upper end to a soft iron orsteel piston 39 which reciprocates within a bell housing made ofnon-magnetic material and attached to the upperend of the reservoir inan airtight manner.

During the course of its movement around the machine the lamp I3 isexhausted while it moves a at the said station-A and is energized one ormore times, depending upon the amount of mercury .to be introduced intothe lamp. The magnetic field produced by the energized coil 4| attractstherethro zh- The pressure member 23 and the cam lever 33 are plvotallymounted on the exv haust head I! within a slot 3l'therein. In theinoperative or open position of the pinchclamp wherein therubbertube 21is left open, the pinch clamp actuating lever or cam 33 occupies an "outposition (as shown in full lines in Fig. 2) wherein it is furtherremoved from the center of rotation of the turret III than it is when inits closed or in" position indicated in dotted lines in Fig. 2. 7

Each exhaust head I! is provided at the top thereof with a separatemercury feeding or injector device 32 for. discharging a measured amountof mercury into the vertical exhaust passageway 23 in the head IS, themercury then passing down through the said passageway and through the'exhaust'tube .I'I into the lamp envelope l4. The mercury feeding device32 may be of any suitable form but preferably is of theelectricallyactuated type disclosed and claimed in copending- U. S.patent application Serial No.

504,716, filed October 2, 1943; by E. B. Isaac et al-., and comprises ahermetically sealed reservoir or container 33 which is filled with aquantity of mercury 34 or other vaporizable metal and is mounted on topthe exhaust head I! with a discharge passageway 38' at the bottom of thereservoir ,in airtight communication with the exhaust passageway 26 inthe exhaust head. A hollow slide or feed member 38, having a smallpocket or recess 31 in its outer side for holdlns and raises the piston33 in the bell housing so as to move the slide member 36 upwardly fromits normal lowered position and introduce the pocket 31 thereof into thepool of mercury 34 .in the reservoir 33. After a brief interval of timesufilcient to allow the pocket 31 to fill with mercury from the pool 34,the coil 4| is de-energized to allow the slide member 33 to fall freelyof its own weight and carry the mercury in the pocket 3! down throughand beyond the restricted portion 33 of the discharge passageway '35-where it drops out of said pocket into the passageway 26 and thence downthrough the said passageway and exhaust tube l1 into the lamp envelope.The required amount of mercury for each lamp is made up by' one or moreactuations of the cuits 42, 42'. The current is supplied to each of thecathodes l5, l5 by'means of a pair of curved plate-shaped track contacts43, 43 and 43', 43'

against which the lamp lead-in wires l6, l6 wipe during the index of thelamp to station A and while it is positioned at said station. The trackcontacts ,43 or 43' for each cathode are connected through separateballasts 44, 44' respecranging from approximately 200 to 250 C. Due. tothe-relatively slow rate of evacuation of the.

3 In accordance with the invention, auxiliary mercury feeding means areprovided for automatically feeding additional amounts of mercury intothe lamp envelope in the event such a mercury deficiency conditionexists therein as indicated either by the total absence of a local arcdischarge or by the absence of a discharge of predetermined minimumintensity, at one or both envelope, a mercury vapor atmosphere is thencreated therein, As a result, a mercury vapor arc discharge will shortlystrike first across the ends of the lowermost cathode l 5 and thenacross the uppermost cathode i5 due to the lower resistance of themercury vapor arc path across each cathode as compared to the resistanceof the cathode itself. The resulting drop in resistance in the cathodeheating circuits 82, 42' which thus occurs when the local arc dischargestrikes across the individual cathodes I5. i5 then causes the currentflowing in the said circuits to increase and the incandescent ballastlamps 44, 44 to burn with appreciably greater brightness thantheretofore.

Inasmuch as the current intensity of the local arc discharge, and thusthe current flow through and therefore the brightness of the ballastlamp 44 or M, increase as the mercury vapor pressure within the envelopeincreases. the relative brightness of the ballast lamp M or 66' at anygiven instant is therefore a. direct indication of the mercury vaporpressure existing at that particular instant within the envelope andthere fore an indication that mercury is present in the envelope in anamount at least equal to the amount required to establish such apressure. Thus, when the ballast lam M or M attains at least apredetermined level of brightness. such condition then denotes thepresence of at least a predetermined amount of mercury within the lampenvelope.

To insure the production of properly performing lamps, it is necessarythat mercury be present in the lamp envelope It in an amount at cathodesI5, l5, the operation of such auxiliary mercury feeding means beinggoverned by suitable control means the operation of which is con--trolled, in turn, by the presence or absence of a local arc discharge ofsuch predetermined minimum intensity at one or both lamp cathodes. Theintroduction of the additional amounts of mercury into the lamp envelopel4 may take place at any time after the lapse of a definite period oftime during which a local arc discharge of such predetermined minimumintensity would be normally expected to occur at one or both cathodes:I5, l5. Preferably, however, the additional mercury is introduced whilethe lamp is positioned at the next succeeding station B (Fig. 2) sinceby that time a local arc discharge of the said predetermined minimumintensity normally should be present at least at the lowermost cathodel5 if the required minimum amount of mercury is present in the lampenvelope.

The auxiliary mercury feeding arrangement according to the inventioncomprises, in general, means for automatically operating the mercuryfeeding or injector device 32 on the exhaust head i9 one or moreadditional times when no local arc discharge, pr a discharge of lessthan the required minimum intensity, is present at one or both lampcathodes, In the particular form of the invention illustrated, theauxiliary mercury feeding arrangement comprises a solenoid coil 45,similar to the coil 4! at station A, which is lowered over the bellhousing of the mercury injector 32 as soon as the latter is positionedat station B. The lowering and raising of the. coil is effected bythechange in shape of a cam $6 mounted on the main drive shaft 41 of leastequal to a predetermined minimum amount.

The mercury feeding device 32 is therefore arranged to feed to theenvelope at station A a quantity of mercurt equal to. but preferablysomewhat in excess of, the said predetermined minimum amount. If all ora sufficient quantity of the mercury thus released by the feeding device32 at station A actually enters the lamp envelope so that the saidenvelope then contains such predetermined minimum amount of mercury.then the mercury vapor created in the lamp envelope by the vaporizationof the mercury therein will shortly attain a predetermined minimumpressure value sufficient to support a local arc discharge ofpredetermined minimum intensity across each of the cathodes l5, I5. Forvarious reasons, however, such as the failure of the mercury feedingdevice 32 to operate properly or lodging of the mercury elsewhere, theamount of mercury which actually enters the lamp at station A issometimes less than the said predetermined minimum amount. The failureof the local arc discharge either to form at the cathodes l5, I5 or toreach a predetermined minimum intensity is. therefore an indication thatthere is either no mercury at all, or less than the required minimumamount of mercury, in the lamp' envelope it.

- the machine and engaging one end of a follower thereby form anenergizing circuit 54 for the said coil. The said solenoid circuit 54 isnormally maintained in an open-circuit condition by 'an interruptingswitch 55. A cam 56, mounted on the main drive shaft 41 and'having oneor more lifts or steps 5'! (preferably three, as shown), in-

termittently closes the said switch 55 for brief intervals, while thecoil 45 is in its lowered posi tion around the bell housing 40, tothereby intermittently operate the mercury injector 32 so as to feedadditional amounts of mercury to the lamp envelope l4.

Connected in the solenoid circuit 54 is a suitable relay device 58 foropening the said circuit when a mercury vapor arc discharge of theaforesaid predetermined minimum intensity exists in the lamp I3 acrossone of the lamp cathodes I5, l5, preferably the lowermost cathode I5.The said relay 58 may be of any suitable type which is responsive toconditions attending the existenceof such a predetermined intensity aredischarge in the lamp to thereby interrupt the solenoid circuit 54.Thus, the relay 58 maybe of the current-sensitive type which is actuatedby a predetermined minimum current flowing therethrough, the relay beingset, for the irposes of the invention, to operate only when the currentflow in the cathode heating circuit 42 or 42' and through'the relayequals or exceeds a predetermined value a determined by the existence ofa local arcdischarge of the aforesaid predetermined minimum intensity atthe cathode l5 or I5. Preferably, however, the relay 58 is of thephotoelectric type which is actuated by an increase in the intensity ofthe light striking the photoelectric cell or tube of the relay. Such aphotoelectric relay may be of the well-known commercial types in use atpresent and it is preferably actuated by the increased light from one orthe other of the ballast lamps 44, 44' in the cathode heating circuits42, 42', the relay being set to operate only when the light from theballast lamp 44 or 44' equals or exceeds a predetermined brightness asdetermined by the existence of a local arc discharge of the aforesaidpredetermined minimum intensity at the cathode l5 orv l5. For adjustingthe intens ty of the light that operates the photoelectric relay,suitable means I are provided such as electrical variables (for instancea resistance) connected in the circuit of the relay itself. or anadjustable or iris" diaphragm 59 interposed between the exciting ballastlamp 44 or 44' and the photoelectr c element'of the relay 58. Ifdesired, the separate indicator or ballast lamp or lamps may be omitted,and the photoelectric relay operated directly by the brilliance of theend glow in the lamp. In that event, a bright glow of predeterminedminimum intensity, due to an arc discharge of the required minimumintensity, indicates ample mercury. and

less brilliance due merely to incandescence of the cathode, indicates adeficiency of mercury.

switch connected in the solenoid circuit 54 and actuated bv the relaycoil. The relay armature or switch 52 is normally maintained in a.closed, ircuit position as shown. and is opened only when thephotoelectric tube 50 is excited by the ballast lamp 4,4 to therebyenergize the relay coil BI and so pull the armature 62 away from therelay switch contact 58.

During substantially the entire indexmovement of the lamp l3 fromstation A to the auxiliary mercury feeding station B, and also while itis positioned at the said station B, the lamp lead-in wires l6, l5 ridealong and en age the track contacts 43, 43' to thereby maintain thecathode heating circu ts 42, 42 closed and therefore the cathodes l5, l5heated. If at least the required minimum amount of mercury has actuallyentered the lamp envelope H at the main mercury filling station A, thenthe substantially continuous heating of the cathodes l5. l5 betweenstations A and B serves to maintain the mercury in the lamp in acontinuously vaporized state to thereby support a mercury vapor arcdischarge of the aforesa d predetermined 'minimum intensity' across thelowermost cathode l5 dur ng the index of the lamp -to station B andwhile it is positioned thereat.

If upon reaching the auxiliary mercury feeding station B a local arcdischarge of the said predetermined minimum intensity persists acrossthe lowermost lamp cathode I5, the ballast lamp 44, because of itsgreatly increased brightness, will excite the photoelectric tube 60 ofthe relay 58 thus causing the relay switch 62 to open and thus break thesolenoid circuit 54 so as to prevent operation of the mercury injector32 at station B. However, if there be no local arc discharge acrossthelowermost cathode [5 when the lamp reaches station B, or if adischarge of less than the aforesaid predetermined intensity is present,then the ballast lamp 44, because of its relatively low or insuflicientbrightness, fails to excite the, photoelectric tube 50 sufficiently tocause the relay switch 52 to open. As a result, the said switch 62remains in its normal closed-circuit position so that when the operatingswitch 55 in the solenoid circuit 54 is subsequently closed by the firststep 51 on the cam 56, the solenoid circuit is completed and the mercuryinjector 32 operated once to feed a definite amount of mercury into thelamp envelope. If, after the introduction of such additional mercuryinto the lamp envelope, a mercury vapor discharge of the requiredminimum intensity should develop across the lowermost cathode I5. thenthe ballast lamp 44 will emit sufficient light to actuate the relay 58and open the solenoid circuit 54 so as to prevent further operation-ofthe mercury injector 32. However, if a mercury vapor arc discharge ofthe required minimum intensity, still fails to occur across thelowermost cathode l5, then the photoelectric relay 5! remains unactuatedand the relay switch 62 remains closed. As a result, the injector 32 isoperated a second time, upon closure of the switch 55 by the second step51 on cam 56, to thereby supply a second shot of mercury to the lamp ii.If, after this second shot of mercury, a mercury vapor arc discharge ofthe required minimum intensity still fails to develop across thelowermost cathode l 5 so that the relay 58 still remains unactuated,then the injector is operated a third time, by the closure of switch 55by the third step on cam 56, to thereby supply a third shot of mer--cury to the lamp.

The three additional shots of mercury automatically supplied by theinjector 32 at the auxiliary mercury feeding station B should result inthe introduction of sufficient mercury into the lamp envelope I4 tocause the formation of a mercury vapor arc discharge of the requiredpredetermined minimum intensity across the lowermost lamp cathode I5 inpractically all cases. If such an arc discharge fails to occur after thethree additional actuations of the mercury injector device 52 at stationB, then such failure is an-indication either that the lamp itself isdefective or that the mercury injector device 32 is not operatingproperly.

To prevent the operation of the auxlliaryimercury injection arrangementat station B in the event there be no lamp present in the head II,

the solenoid circuit 54 is preferably provided with a suitable cutoutswitch 64 for interrupting the said circuit when such condition exists.The said switch 64 is preferably actuated by the pinch clamp lever 30,the switch normally being in an open-circuit position and being engagedby the pinch clamp operating lever 30 when the latter is in its outposition (indicating the presence of a lamp in the head) to therebyclose the switch duringthe interval when the head I l is positioned2,374,304 at station B. The switch 6| may be mounted on an arm 65extending from the stationary standard 65 through which the solenoidcoil support rod l9 extends, the switch being located in a position inthe path of the rotary travel of the pinch clamp lever 30, when thelatter is in its out position as shown in Fig. 2, so as to be engagedand actuated thereby when in such position. If desired, a suitableindicator lamp 61 may be connected in the solenoid circuit 54 inparallel with the solenoid coil 65 for the purpose of indicating whetheror not the auxiliary mercury feeding arrangement is operating to supplyadditional mercury to the lamp at station B.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In combination, means for feeding a quantity of vaporizable metalinto an envelope, means for vaporizing the vaporizable metal introducedinto the envelope, means including an electrical circuit forestablishing an arc discharge through the metal vapor, means controlledby said electrical circuit for detecting the existence of a discharge ofpredetermined minimumintensity', and means controlled by the detectingmeans for operating the said feed means to feed an addi tional amount ofthe vaporizable metal into the envelope upon nonexistence of such aminimum intensity discharge.

2. In combination, means for feeding a quantity of vaporizable metalinto an envelope, means for vaporizing the vaporizable metal introducedinto the envelope, means including an electrical circuit forestablishing an arc discharge through the metal vapor, said electricalcircuit including an electric lamp connected therein to provide anindication of the existence of an arc discharge of predetermined minimumintensity, and means controlled by the light output of said lamp foroperating the said feed means to feed an additional amount of thevaporizable metal into the envelope upon non-existence of such a minimumintensity discharge. 4

3. In combination, means for feeding a quantity of vaporizablenietalinto an envelope, actuating means for the feed means, means forvaporizing the vaporizable metal introduced into the envelope, meansincluding an electrical circuit for establishing an arc dischargethrough the metal vapor, said electrical circuit including an electriclamp connected therein to provide an in-- dication of the existence ofan arc discharge of predetermined minimum intensity, and photoelectricrelay means responsive to the light output of said lamp for controllingthe operation of said actuating means to cause the feeding of anadditional amount of the vaporizable metal into the envelope by the saidfeed means upon nonexistence of such a minimum intensity discharge.

4. In combination, electrically actuated means for feeding a quantity ofvaporizable metal into an envelope, means including an electricalactuating circuit for operating the feed means, means for vaporizing thevaporizable metal introduced into the envelope, means including anelectrical circuit for establishing an arc discharge through the metalvapor, and means controlled by the said last-named arc establishingcircuit for controlling the operation of said actuating circuit topredetermined minimum intensity.

5. In combination, means for feeding a quantity of vaporizable metalinto an envelope, means for vaporizing the vaporizable metal introducedinto the envelope and for establishing an arc discharge through themetal vapor, said last-named means comprising an electrical heatingelement in the envelope and an electrical circuit for said heatingelement, and means controlled by the nonexistence of a discharge ofpredetermined minimum intensity for operating the said feed means tofeed an additional amount of the vaporizable metal into the envelope.

6. In combination, means for feeding a quantity of vaporizable metalinto an envelope, means for vaporizing the vaporizable metal introducedinto the envelope and for establishing an are discharge through themetal vapor, said last-named means comprising an electrical heatingelement in the envelope and an electrical circuit for said heatingelement, and means controlled by said electrical circuit for operatingthe said feed means I means comprising an electrical heating element inthe envelope and an electrical circuit for said element including anelectric lamp connected to provide an indication of the presence of adischarge of predetermined minimum intensity, and

means controlled by the light output of said lamp for operating the saidfeed means to feed an additional amount of the vaporizable metal intothe envelope upon nonexistence of such a minimum intensity discharge.

8. In combination, electromagnetically actuated feedmeans for feeding aquantity of vaporizable metal into an envelope, an electrical actuatingcircuit including a solenoid for operating said feed means, means forvaporizing the vaporizable metal introduced into the envelope, meansincluding an electrical circuit for establishing an arc dischargethrough the metal vapor, andmeans controlled by the said last-namedarc-establishing circuit for controlling-the operation of the solenoidactuating circuit to cause the feeding of an additional amount of thevaporizable metal into the envelope by the said feed means uponnonexistence of a discharge of predetermined minimum intensity.

9. In combination, electromagnetically actuated feed means for feeding aquantity of vaporizable metal into an envelope, an electrical ac.-tuating circuit including a solenoid for operating said feed means,means for vaporizing the vaporizable metal introduced into the envelopeand for establishing an arc discharge through the metal vapor, saidlast-named means-comprising an electrical heating element in theenvelope and an electrical heating circuit for said element, and meanscontrolled by said heating circuit for controlling the operation of thesolenoid circuit to cause the feeding of an additional amount oi thevaporizable metal into the envelope by the said feed means uponnonexistence of a discharge predetermined minimum intensity.

10. In combination, electrically actuated al paratus for automaticallyfeeding mercury into the envelope of an electrical device containin aresistance heating element, means for effecting a repeat operation ofthe feeding apparatus when its initial operation fails to introducesufllcient mercury into the enevelope comprising an electrical circuitincluding an electric lamp connected in series with said heating elementto a current source so that said heating element is heated to establishthereacross an arcdischarge through the mercury vapor whereby said lampis lighted to a lower lever of brilliance when current is passingthrough the heating element and to a higher predetermined level when anarc is established, and light-sensitive relay means responsive to thelight emitted by said lamp and connected to efl'ect a repeat operationof the feeding apparatus only upon failure of the lamp to be lighted tothe higher predetermined level of brilliance.

11. An indexing type lamp exhaust apparatus comprising, in combination,a carrier member having a lamp-supporting head mounted thereon andindexed thereby to a plurality of worl: stations. mercury feed means onsaid head for feeding mercury into a lamp mounted in the head, actuatingmeans at one of said stations for operating said feed means to therebyfeed a quantity of mercury to the lamp, means at a subsequent stationfor determining the presence or absence of a predetermined minimumamount of mercury in the lamp, and means controlled by said last-namedmeans for operating the said feed means at said subsequent station tofeed an additional amount of mercury to the lamp when less than the saidminimum amount of mercury is present therein.

12. An indexing type lamp exhaust apparatus comprising, in combination,a carrier member having a lamp-supporting head mounted thereon andindexed thereby to a plurality 01' work stations, electrically actuatedmercury feed means on said head for ieeding mercury into a lamp mountedin the head, electrical actuating means for operating said feed means atone of said stations to thereby feed a quantity of mercury to the lamp,means for vaporizing the tion.

vaporizable metal introduced into the envelope, means including anelectrical circuit for establishing an arc discharge through the mercuryvapor in the lamp at a subsequent station, auxiliary actuating means foroperating said feed means at the said subsequent station, and meanscontrolled by the arc-establishing circuit for controlling the operation01 said auxiliary actuating cury feeding device on said head for feedingmercury into a lamp mounted in the head, electromagnetic actuating meansfor operating said feeding device at one of said stations to therebyfeed a quantity of mercury to the lamp, means for vaporizing thevapcrizable metal introduced into the envelope, means including acathode in the lamp and an electrical heating circuit for said cathodefor establishing an arc discharge through the mercury vapor in the lampat a subsequent station, auxiliary electromagnetic actuating meansincluding an electrical actuating circuit for operating said feed meansat the said subsequent station, and a relay connected in said actuatingcircuit and controlled by the said heating circuit for-controlling theoperation of said auxiliary actuating means to cause the feedmg of anadditional amount of mercury to the lamp .by the said feed meansupon'nonexistence of an arc discharge of predetermined minimum intensityin the lamp at the said subsequent sta- CHARLES E. OWINGS.

